Measured amounts of various fluid substances are increasingly commonly dispensed in relatively small flexible packages often composed of plastic or foil. The fluids include a wide variety of products, including foodstuffs such as condiments, personal care products such as shampoos, and pharmaceutical products such as medications.
A typical example is that of the ubiquitous single serving ketchup pack, which is generally formed of two sheets of foil or plastic, superimposed over one another, and then sealed together around the periphery, with a notch or other means to facilitate tearing one edge away from the container. The user tears open the container, dispenses the condiment, and then disposes of the package. More sophisticated examples include varieties of BFS (blow-fill-seal) packaging, in which a frangible plastic shell is blown, filled with a fluid, and then sealed, in a continuous operation. Some portion of the BFS container formed by this method is severed or otherwise broken at the time of use, and the fluid is dispensed, most often by manually squeezing the container.
These types of packages, while effective for certain types of fluids, are particularly troublesome for packaging designed to dispense more than a single discrete fluid at the same time. The need for such a dispensing apparatus arises from the fact that many substances, particularly medicaments, are preferably stored as separate components that are optimally mixed at the time of dispensing and use. Often, this is due to the fact that such components, when combined, result in mixtures that are either unstable or have a limited shelf life after mixing. An example of a simple dispensing container of this nature is seen in U.S. Pat. No. 5,843,409 ('409) to Campbell et al., in which separate compartments of a dentifrice tube may be squeezed, expelling separate components from an egress neck that, when not in use, is covered by a cap commonly covering both fluid compartments.
Various problems present themselves in designing a package designed to seal the component fluids from the environment, and then after the seal is broken, to mix and dispense more than a single discrete fluid at one time. Firstly, since such packaging must allow for the simultaneous and controlled opening of separate chambers, the opening mechanism must irreversibly and cleanly open all fluid containing chambers. The packaging can be quite difficult to open, particularly for those with arthritic hands or otherwise weakened grip strength. This difficulty is exacerbated by the fact that the container must be relatively strong in order to contain the contents under normal handling conditions, which may include accidental compression. Even a small amount of moisture or skin oil on the surface of the packaging can make gripping and tearing the often small package nearly impossible. It is extremely common to see frustrated users of such packaging using their teeth to open ostensibly manually “tear open” packages. Such a technique poses obvious aesthetic and hygienic issues; not to mention the dangers associated with products that are not safe for oral contact. A typical example of such packaging is seen in U.S. Pat. No. 6,247,617 ('617) to Clyde et al., in which side-by-side fluid chambers within a single container are each connected by egress necks to a common seal. When the seal is broken, the fluid may be expelled from the chambers.
Such packaging raises problems of its own. Firstly, it can be difficult to grasp the container tightly enough to grip it and break off the dispensing neck without putting significant pressure on the sidewalls of the fluid filled chambers. Then, when the dispensing neck breaks off, a possibly considerable amount of the chamber contents can be prematurely expelled. Secondly, the goal of the separated chambers is generally to effect a mixing in a predetermined ratio of the fluids. One method to achieve such a predetermined ratio is seen in U.S. Pat. No. 3,197,071 ('071) to Kuster, in which it is specified that the egress necks of the separated chambers may be varied in size so as to achieve a desired ratio of the mixture of the fluids. Depending on the volume and viscosity of the fluids, it may be difficult to achieve the correct ratio. Particularly, if more pressure is exerted on one chamber than on another, as may easily be done when manually gripping side by side chambers such as those described in the '617 device, there can be marked variation in the amount of contents expelled from each of the chambers. As an additional issue, many substances are ideally packaged in child-resistant form, to protect young children from accessing the contents.